At 9:15pm on the 19th January 2013, Christchurch and Canterbury were shaken by a 4.6 aftershock that was centred near Rolleston. It was the largest shake the area has had in over six months. Canterbury Quake Live recorded the magnitude as 4.62 at 12 kilometres deep and it released 128 tonnes of energy. It measured V on the Mercalli Scale meaning that it was ‘Felt by almost everyone, some people awakened. Small objects moved. Trees and poles may shake.’
The Canterbury Quake Live website was swamped with hits within minutes with the usual 100 or 200 online swelling to over 16,000. Facebook and Twitter were also buzzing with news and comments included the following:
“I saw the walls of our lounge moving from side to side.”
“Really violent quake just now.”
“That woke me up.”
“That was strong.”
The 4.6 aftershock was followed by a 2.38 shake at 9:48pm and a 2.22 at 10:00pm.